US President Donald Trump's son Eric has said that his father's decision to launch a missile attack on a Syrian airbase was influenced by the reaction of his sister Ivanka.

US President Donald Trump's son Eric has said that his father's decision to launch a missile attack on a Syrian airbase was influenced by the reaction of his sister Ivanka.

He said that the decision to punish President Bashar al-Assad for an alleged chemical weapons attack which killed civilians, was taken after his sister was "heartbroken and outraged" by the atrocity.

Eric also said the action proved that his father was not in league with Russia and would not be "pushed around" by Vladimir Putin, The Daily Telegraph reported.

Eric Trump said his father was not intimidated by President Putin's talk of war, and there would be "no-one harder" than President Trump if they "cross us".

The comment came as Foreign Secretary Boris Johnson said Russia would face fresh sanctions if it did not pull its armed forces out of Syria and end its support for Assad.

As foreign ministers of the G7 group of nations met to agree the best way to put pressure on Mr Putin, Johnson said the US missile strike had "changed the game" and Russia now "needs a way out" because association with Assad's "toxic regime is...poisoning the reputation of Russia", the report said.